All About Cloning

Types, Technique, Animals and More

Dolly (the first cloned sheep), and three other sheen in a field.
Dolly (far right), the first mammal cloned from an adult cell, bleats at Scotland's Roslin Institute. Karen Kasmauski / Getty Images

Cloning is the process of creating genetically identical copies of biological matter. This may include genes, cells, tissues or entire organisms.

Natural Clones

Some organisms generate clones naturally through asexual reproduction. Plants, algae, fungi, and protozoa produce spores that develop into new individuals that are genetically identical to the parent organism. Bacteria are capable of creating clones through a type of reproduction called binary fission. In binary fission, the bacterial DNA is replicated and the original cell is divided into two identical cells.

Natural cloning also occurs in animal organisms during processes such as budding (offspring grows out of the body of the parent), fragmentation (the body of the parent breaks into distinct pieces, each of which can produce an offspring), and parthenogenesis. In humans and other mammals, the formation of identical twins is a type of natural cloning. In this case, two individuals develop from one fertilized egg.

Types of Cloning

When we speak of cloning, we typically think of organism cloning, but there are actually three different types of cloning.

  • Molecular Cloning: Molecular cloning focuses on making identical copies of DNA molecules in chromosomes. This type of cloning is also called gene cloning.
  • Organism Cloning: Organism cloning involves making an identical copy of an entire organism. This type of cloning is also called reproductive cloning.
  • Therapeutic Cloning: Therapeutic cloning involves the cloning of human embryos for the production of stem cells. These cells could be used to treat disease. The embryos are eventually destroyed in this process.

Reproductive Cloning Techniques

Cloning techniques are laboratory processes used to produce offspring that are genetically identical to the donor parent. Clones of adult animals are created by a process called somatic cell nuclear transfer. In this process, the nucleus from a somatic cell is removed and placed into an egg cell that has had its nucleus removed. A somatic cell is any type of body cell other than a sex cell.

Cloning Problems

What are the risks of cloning? One of the main concerns as it relates to human cloning is that the current processes used in animal cloning are only successful a very small percentage of the time. Another concern is that the cloned animals that do survive tend to have various health problems and shorter lifespans. Scientists have not yet figured out why these problems occur and there is no reason to think that these same problems wouldn't happen in human cloning.

Cloned Animals

Scientists have been successful in cloning a number of different animals. Some of these animals include sheep, goats, and mice.

Cloning and Ethics

Should humans be cloned? Should human cloning be banned? A major objection to human cloning is that cloned embryos are used to produce embryonic stem cells and the cloned embryos are ultimately destroyed. The same objections are raised with regard to stem cell therapy research that uses embryonic stem cells from non-cloned sources. Changing developments in stem cell research, however, could help ease concerns over stem cell use. Scientists have developed new techniques for generating embryonic-like stem cells. These cells could potentially eliminate the need for human embryonic stem cells in therapeutic research. Other ethical concerns about cloning involve the fact that the current process has a very high failure rate. According to the Genetic Science Learning Center, the cloning process only has a success rate of between 0.1 to 3 percent in animals.

Sources

  • Genetic Science Learning Center. "What are the Risks of Cloning?". Learn.Genetics. June 22, 2014.